Roof supports for mine workings



May 23, 1961 A. w. DUNCAN ROOF SUPPORTS FOR MINE WORKINGS 2 Sheets-Sheet 1 Filed June 9, 1958 W ALM May 23, 1961 A. w. DUNCAN ROOF SUPPORTS FOR MINE WORKINGS 2 Sheets-Sheet 2 Filed June 9, 1958 United States Patent ROOF SUPPORTS FOR MINE WORKINGS Angus Wellesley Duncan, Leigh Sinton, near Malvern,

England, asslgnor to. The Mining Engineering Company Lumted, Worcester, England, a British company Filed June 9, 1958, Ser. No. 740,813

6 Claims. (Cl. 248-356) This invention relates to improvements in root supports for mine workings and the like.

Many dilfer'ent forms of roof support have been proposed, and most of these incorporate means for collapsing them or for reducing their etfective height to allow the supports to be moved forwardly into fresh positions to follow up the removal of the coal or other mineral. The supports are usually pre-loaded to take the weight of the roof, and a support or at least part of it, is usually arranged to yield to some extent under an excessive load such as that caused by subsidence of the roof of the 2 working.

According to our invention, a roof support for mine workings incorporates at least one reinforced rubber or like tyre filled with fluid under pressure and mounted with its axis vertical.

Where the roof support incorporates a number of tyres, these are super-imposed with their axes vertical and in substantial alignment, the tyres being in direct communication with each other.

The tyres may be similar to the usual tyres fitted to road vehicles, and may be mounted in any convenient manner permitting approach of the walls of the individual tyres under load, and maintaining the tyres substantial-1y in axial alignment.

The side walls of the tyres are in contact with each other, and when the axial length of the support varies, practically the whole of the flexing of the tyres will be limited to the treads.

A support of any desired height can be obtained by selection of the appropriate number of tyres in the assembly.

For use in very low seams, a support comprising a single tyre may be suflicient, but for seams of normal height a support will incorporate a number of superimposed tyres.

The tyre assembly may be combined with an hydraulic accumulator.

Two practical forms of roof support in accordance with our invention are illustrated diagrammatically by way of example in the accompanying drawings in which:

Figure 1 is a vertical section of a chock formed by an assembly of tyres,

Figure 2 is a plan of the chock shown in Figure 1,

Figure 3 is a vertical section of a chock embodying an hydraulic accumulator,

Figure 4 is an elevation in part section of the accumu lator alone.

In the roof support shown in Figures 1 and 2, three superimposed tyres 10, 11, 12 are arranged about a common vertical axis. The tyres are of rubber reinforced with fabric or with steel or other cords, and may be identical with or similar to ordinary vehicle tyres. The adjacent beads of the tyres are spaced by rigid steel rings 13 which are located between them and against which they are clamped by annular pressed steel plates 14 located inside the tyres and secured together by bolts 15. The top head of the uppermost tyre is clamped by an annular plate 16 against a top plate 17 and the bottom bead of the lowermost tyre is clamped by an annular plate 18 against a rigid bottom plate 19 adapted to engage the floor of the mine workings.

The top and bottom plates 117 and 19 are conveniently of rectangular outline as shown in Figure 2, and the top plate carries a downwardly extending central tube 20 into which a tube 21 extending upwardly from the bottom plate 19 is adapted to telescope. These tubes extend through the annular clamping plates and keep the tyres in axial alignment.

A passage 22 in the upper plate communicating with the interior of the tyres, which are all in direct communication with each other through the openings in the clamping rings, has at its outer end a connection 23 for a pipe by which fluid under pressure is forced into the tyres. A second passage 24 also communicating with the interior of the tyres has at its outer end a springloaded valve 25 which acts as a relief valve limiting the maximum pressure to which the tyres can be subjected under load, and can also be opened manually to allow fluid to escape for collapsing the support.

,When setting up the support, the tyres are filled with liquid under pressure from any convenient source through the connection 23. In many mine workings, fire mains are available carrying water at pressures up to 700 pounds per square inch and it will be convenient to fill the tyre assembly with water drawn from such mains.

Figure 1 shows the tyre assembly filled with liquid under pressure and it will be observed that while the walls of the tyres are in contact, the clamping rings are spaced at a substantial distance apart. When the load on the support is increased by root subsidence, the support can contract in heigh't'by expansion of the tyres radially and circum-ferentially, any flexing which takes place being confined substantially-to the radially outermost surfaces or treads of the tyres.

If the pressure in the tyres exceeds a predetermined value owing to increased load on the support, liquid will be vented from the valve 25 until the pressure is reduced to the value determined by the setting of the valve.

When it is desired to collapse the support for moving, the valve 25 is opened to allow liquid to escape firom the tyres and when the support has been moved to its new position, the valve 25 is closed and the tyres are filled again with liquid under pressure through the connection 23.

A roof support may comprise an assembly of tyres as described above in combination with an hydraulic accumulator as shown in Figures 3 and 4. In this arrangement, the bottom bead of the lowermost tyre 12 of the assembly is clamped to a plate 29 at the upper end of a closed chamber 30 forming the lower part of the support. The support comprises the plate 29, a base-plate 31, and a peripheral wall 32 welded at its top and bottom ends to the plates.

A tyre 33 is mounted in the chamber with its bottom bead clamped against the base plate by an annular clamping plate 34, and its upper head is clamped by an annular clamping plate 35 against a closure disc 36. The interior of the tyre communicates through a passage 37 in the base plate with a connection 38 through which air under pressure can be forced into the tyre. A manually operated valve 39 in the plate 34 controls communication between the tyre assembly and the chamber 30. Another manually operated valve 40 controls the release of fluid from the tyre assembly, and a spring-loaded automatic non-return valve 41 allows fluid to pass from the tyre assembly into the chamber 30 when the pressure in the tyre assembly exceeds a predetermined value.

The tyre 33 is filled with air or other gas under pressure and the tyre assembly and the chamber 30 are filled with water or other liquid under pressure.

When the support yields under roof pressure, liquid is forced from the tyre assembly into the chamber 30 and the tyre 33 is compressed and energy is stored in the form of an increase in the air pressure in the tyre.

If subsidence of the roof continues after the accumulator is fully loaded surplus liquid will be vented from the tyre assembly through a relief valve 42 corresponding to the valve 25 in Figure 1.

To collapse the support for moving the valve 39 is closed and liquid is vented from the tyre assembly by opening the valve 40. When the support has been moved to a fresh position, the valve 40 is closed and the tyre assembly is filled with liquid again from any convenient source under pressure to bring the top plate up into contact with the roof. The support is then preloaded by opening the valve 39 which allows liquid in the chamber 30 under the pressure exerted on it by the tyre 33 to pass into the tyre assembly.

The tyre 33 may be replaced by any other form of flexible and expansible member such as a rubber bag designed to withstand the working pressure.

I claim:

1. A roof support for mine workings comprising a plurality of superimposed reinforced rubber tyres having their axes vertical and substantially in alignment and having their adjacent side walls in contact, the tyres being filled with liquid under pressure and being in communication with each other.

2. A roof support for mine workings comprising a plurality of inter-communicating reinforced rubber tyres assembled together with their axes vertical and in substantial alignment and their adjacent walls in contact, means for clamping together in fluid tight engagement the adjacent beads of the tyres, a rigid top plate, means for clamping the upper bead of the uppermost tyre to the top plate, a rigid bottom plate, means for clamping the bottom bead of the lowermost tyre to the bottom plate, means for introducing liquid under pressure into the tyres, a relief valve for limiting the maximum pressure of liq- 4 uid in the tyres, and means for venting liquid from the tyres.

3. A roof support for mine workings comprising a plurality of intercornmunicating reinforced rubber tyres adapted to be filled with liquid under pressure and assembled together with their axes vertical and in substantial alignment and their adjacent 'walls in contact, in combination with an hydraulic accumulator forming part of the support and means controlling communication between the tyre assembly'and the accumulator;

4. A roof support for mine workings as in claim 3 wherein said means controlling communication between the tyre assembly and the accumulator comprises a manually operated valve and an automatic non-return valve permitting the passage of liquid from the tyre assembly into the accumulator, and a further manually operated valve is provided for venting liquid from the tyre assembly.

5. A roof support for mine workings as, in claim 3 wherein said accumulator comprises a rigid closed chamber and a flexible and expansible member located within the chamber and adapted to be filled with air under pressure.

6. A roof support for mine workings as in claim 3, wherein said accumulator comprises a rigid closed chamber and a closed reinforced rubber tyre located within the chamber and adapted to be filled with air under pressure. I

References Cited in the file of this patent UNITED STATES PATENTS 2,536,626 Coleman Jan. 2, 1951 FOREIGN PATENTS 673,579 Great Britain June 1 1, 1952 1,016,105 France Aug. 20, 1952 1,082,903 France Jan. 4, 1955 1,001,127 Germany Jan. 17, 1957 

